That is a "category of one", Firefly is it, not to be confused with Outback "nano carbon".
And 20% DoD is the lowest I'd go myself, sizing for usually 30-40% will give you more cycled.
The sulfation recovery process every once in a while takes a bit of skill/knowledge, equipment and attention, but it's not rocket science.
Next best thing to LiFePO4 for PSOC situation, not nearly as expensive.
But jury is still out on longterm/widespread feedback to confirm Nigel Calder & Maine Sail's testing results.
Which it looks like I lost the link for, was in Practical Sailor magazine.
Note Bruce from that video, the inventor of the Firefly, Nigel and MS all live near each other there in Maine, you may hear some (not me) say that as if a reason to be skeptical.